1. Field of the Invention
This invention relates generally to tension leg cables for use with tension leg platforms, and more particularly, but not by way of limitation, to a multi-strand cable having a vulcanized rubber sheath covering said cable with an inert gas under pressure provided to voids between strands of said cable.
2. Description of the Prior Art (Prior Art Statement)
The following is intended to be a prior art statement in accordance with the guidance and requirements of 37 C.F.R. 1.56, 1.97 and 1.98.
U.S. Pat. No. 3,517,517 to Blenkarn discloses a cable for use in tethering a tension leg platform. The system of Blenkarn comprises a wire cable having a metal sheath disposed thereabout and having a fluid such as oil in the annulus between the wire cable and the metal sheath. No disclosure is made of monitoring fluid pressure within the permeable zone within the steel cable itself, or within the annulus between the sheath and the cable.
U.S. Pat. No. 2,438,411 to Hollingsworth, and No. 2,004,769 to Shanklin, each disclose a system for maintaining a positive pressure of a fluid within an annular space between a sealed conduit and an electric cable to prevent entry of corrosive fluids and for insulating purposes. The fluid pressure in the annulus is monitored to detect leaks in the conduit. No disclosure is made of monitoring fluid pressure in the permeable zone or voids within the steel cable itself.
U.S. Pat. No. 3,979,896 to Klett et al. discloses a wire cable having a lubricant entrapped between the strands and sheathed with a plastic sheath. U.S. Pat. No. 3,800,522 to Hughes et al. discloses a wire cable impregnated with a foamed plastic sealant.
U.S. Pat. No. 3,300,573 to Ronald et al. and No. 2,105,168 to Staples disclose electrical cables sheathed with plastic insulation which is in turn covered with a metal sheath.
U.S. Pat. No. 3,457,717 to Durkee et al., No. 3,339,012 to Hutchins, Jr., and No. 2,142,625 to Zoethout are illustrative of the state of the art in sheathed electrical cables.
Thus it is seen that none of these prior art references disclose a tension leg cable having a pressurized fluid within the voids between strands of the cable itself and a means for monitoring the pressure of that fluid to detect leaks in a sheath covering the tension leg cable.